Question

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Why does this code crash?

Please tell me whats wrong with the following code???Why is it crashing???

I cant store the collatz values in the array however if I want to print them individually it works perfectly.

#include <iostream>
long collatz(long);

int main()
{
  using namespace std;
  long i=3,t[1000000],p;
  t[0]=0,t[1]=0,t[2]=0;
  for(i=3; i<1000000; i++)
  {
    p=collatz(i);
    t[i]=p;
  }
  cin.clear();
  cin.get();
}


long collatz(long n)
{
  long count=0;
  do {
    if (n%2==0)
    {
      n=n/2;
      count+=1;
    }
    else
    {
      n=((3*n)+1);
      count+=1;
    }
  } while(n!=1);
  return count;
}

Answer 1

It’s likely that stack allocation for:

long t[1000000]; fails. So when you actually write into the array, it invokes undefined behaviour.

Allocate dynamically or use standard containers.